Major General Henry Wagner Halleck
6th grandson of Peter Hallock "The immigrant"
Much of the following information provided through the research of Amy Luciano.
    The line and descendancy of Henry Wagner Halleck can be seen within the Hallock Surname file on Long Island Genealogy

Major General Henry Wagner Halleck

   Halleck, Henry W., major-general, was born at Westernville, Oneida, county, N. Y., Jan. 16, 1815. After a common-school education, received at Hudson academy, and a partial course at Union college, he entered the United States military academy July 1, 1835, graduating four years later third in a class of thirty-one. On July 1, 1839, he was appointed second lieutenant in the engineer corps of the army, and from his marked ability and skill as an instructor, while still a cadet, was retained as assistant professor of engineering at the academy until June 28, 1840. During the next year he acted as assistant to the board of engineers at Washington, D. C., and was thence transferred to assist in the construction of the fortifications in New York harbor. Here he remained several years, with the exception of time spent in 1845 on a tour of inspection of public works in Europe, receiving while absent a promotion to first lieutenant. At the outbreak of the war with Mexico, he was sent to California as engineer of military operations for the Pacific coast, and after a seven-months, voyage in the transport Lexington, reached Monterey, Cal., which he partially fortified as a port of refuge for the Pacific fleet, and a base for incursions into California by land. In his military capacity he accompanied several expeditions; in that of Col. Burton into Lower California, he acted as chief of staff to that officer, and took part in the skirmishes of Palos Prietos and Urias,
Nov. 19-20, 1847; with a few volunteers made a forced march to San Antonio, March 16, 1848, surprising a large Mexican garrison and nearly capturing the governor, and was engaged at Todos Santos on March 30. He was also aid-de-camp to Com. Shubrick in naval operations on the coast, among which was the
capture of Mazatlan (of which for a time he was lieutenant-governor), and for "gallant and meritorious services," received the commission of captain by brevet, to date from May 1, 1847. As secretary under the military governments of Gens. Mason and Riley, he displayed "great energy, high administrative qualities, excellent judgment and admirable adaptability to his varied and onerous duties," and as a member of the convention, called to meet at Monterey, Sept. 1, 1849, to
frame a constitution for the state of California, he was substantially the author of that instrument. On Dec. 21, 1852, he was appointed inspector and engineer of lighthouses; from April 11, 1853, was a member of the board of engineers for fortifications of the Pacific coast, receiving the promotion of captain of engineers on July 1 and retained all these positions until Aug. 1, 1854, when he resigned from the army to become the head of the most prominent law firm in San Francisco, with large interests and much valuable property in the state, with whose development and prosperity his name was identified. In 1860-61 he was major-general of the militia of California, and at the outbreak of the Civil war tendered his services to the government, and was appointed major-general of recommendation of Gen. Scott, his commission dating Aug. 19, 1861 regulars at the urgent. On Nov. 18 he took command of the Department of Missouri, with headquarters at St. Louis,
where his vigorous rule soon established order. After the victory at Shiloh Halleck took the field, having, March 11, 1862, succeeded to the command of the Department of the Mississippi, and the siege of Corinth took place under his personal direction. After the evacuation by the enemy, and in the midst of the fortification of Corinth against his return from the south, Halleck was visited by two assistant secretaries of war and one U. S. senator, to urge his acceptance of the office of general-in-chief, which had been tendered him, but which he declined until events in the Peninsular campaign forced his acceptance of the honor on July
From Washington, on Oct. 28, he wrote the letter which constitutes "the only official explanation of the final removal of McClellan from command, Nov. 7." After Gen. Grant became lieutenant-general of the army, Halleck remained at Washington as chief of staff March 12, 1864, to April 19, 1865 and from April 22 to July 1 of the latter year was in command of the military division of the James with headquarters at Richmond. On Aug. 30 he took command of the division of the Pacific, from which he was relieved by Gen. George H. Thomas, and on March 16, 1869, was transferred to that of the South, with headquarters at Louisville, Ky. Gen. Halleck died at Louisville, Jan. 9, 1872. - Source: The Union Army, vol. 8

This picture of President Lincoln on his deathbed was found in the Hallock family album of Amy Luciano.  It is an engraving by C.A. Asp of Washington, DC.  The engraving has been praised for its realism.  Supposedly it is a rare find, because it wasn't popular at the time, probably due to that same realism.
NOTE: Henry would be the one standing fifth from the left

On the web page "News of Abraham Lincoln's Death," the following quote lists those at the bedside of President Lincoln during his last moments:
Surrounding the death bed of the President were Secretaries Stanton, Welles, Usher, Attorney-General Speed, Postmaster-General Dennison, M.B. Field, Assistant Secretary of the Treasury; Judge Otto, Assistant Secretary of the Interior; Gen. Halleck, Gen. Meigs, Senator Sumner, R.F. Andrews, of New-York; Gen. Todd, of Dacotah; John Hay, Private Secretary; Gov. Oglesby, of Illinois; Gen Farnsworth, Mr. and Miss Kenney, Miss Harris, Capt. Robert Lincoln, son of the President, and Doctors E.W. Abbott, R.K. Stone, C.D. Gatch, Neal Hall, and Mr. Lieberman. Secretary McCulloch remained with the President until about 5 o'clock, and Chief Justice Chase, after several hours' attendance during the night, returned early this morning.

Halleck, Henry Wager
The Twentieth Century Biographical Dictionary of Notable Americans: Volume V page 42
HALLECK, Henry Wager, soldier, was born in Westernville, N.Y., Jan. 16, 1815. He was a descendant of Peter Halleck (or Hallock) of Long Island, 1640, and of Henry Wager, an early settler of central New York. He matriculated at Union college, and was graduated at the U.S. military academy in 1839, third in a class of thirty-one. He was appointed 2d lieutenant in the engineer corps and was retained at the academy as assistant professor of engineering and on July 28, 1840, was transferred to the board of engineers, Washington, D.C., as assistant. He was engaged on the fortifications in New York harbor, 1840-17, and during the period visited Europe on a tour of inspection of public works. He was promoted 1st lieutenant in 1845 and in 1847 was ordered to California as engineer for the western coast. He sailed on the transport Lexington, landed at Monterey, Cal., which he made a military base by fortifying the port, and which also became the rendezvous of the Pacific squadron. He accompanied several expeditions; was chief of staff to Colonel Burton, and took part in various skirmishes in Lower California in November, 1847; commanded the volunteers who marched to San Antonio, and on March 16, 1848, surprised the Mexican garrison and engaged in a skirmish at Todos Santos, March 30; and aided Commodore Shubrick. U.S.N., in the capture of Mazatlan, of which place he was for a time lieutenant-governor. He was brevetted captain to date from May 1, 1847, for "gallant and meritorious services" in these engagements. He was military secretary to military governors Mason and Riley and was commended for "great energy, high admimstrative qualities, excellent judgment and admirable adaptability to his varied and onerous duties." He was a member of the convention that met at Monterey, Sept. 1, 1849, to frame a constitution for California, wrote the instrument, and refused to represent the state in the U.S. senate, preferring to continue his service in the army as aide-de-camp on the staff of General Riley. He was inspector and engineer of lighthouses, 1852-53; a member of the board of engineers for fortifications on the Pacific coast. 1853-54; was promoted captain of engineers, July 1, 1853, and resigned from the army, Aug. 1, 1854, to become bead of a law firm of San Francisco, with large landed interests in the state. He was director-general of the New Almaden quicksilver mines, 1850-61; president of the Pacific & Atlantic railroad from San José to San Francisco, 1855-61; major-general of the state militia, 1860-61, and early in 1861 was appointed at the urgent recommendation of General Scott, major-general in the U.S. army, his commission dating from Aug. 19, 1861. He was commander of the department of Missouri, which embraced western Kentucky, Illinois, Wisconsin, Minnesota, Iowa, Missouri and Arkansas, with headquarters at St. Louis. He brought to this position a military training and experience that in three months placed the Federal army in possession of all the territory under his control, save southern Missouri and western Kentucky, and then, with the aid of the gunboat flotilla of Admiral Foote and the army of General Grant, be began the military operations that resulted in the capture of Forts Henry and Donelson; the possession of Bowling Green, Columbus and Nashville; of New Madrid, Columbus and Island No. 10 on the Mississippi, and of the whole of Missouri and northern Arkansas, establishing the Federal army on a line extending from Chattanooga to Memphis. The departments of Kansas and Ohio were placed in his department, March 11, 1862, and the whole became known as the department of the Mississippi, which included the territory between the Alleghany and Rocky mountains. After the battle of Shiloh, General Halleck personally took the field and moved against Corinth, which had been fortified by the Confederate army, and on reaching the place May 30, it fell into his bands without an assault, the enemy having evacuated the place. He directed the pursuit of the fleeing Confederates, General Pope following up the direct retreat, while Sherman marched to Memphis, already captured by the gunboats before his arrival, and Buell marched against Chattanooga. He held the fortifications at Corinth, repaired railroad communications, and prepared to operate against Vicksburg, when on July 23 be accepted the appointment, made by President Lincoln, as general-in-chief of the armies of the United States with headquarters at Washington, D.C. He at once ordered the withdrawal of McClellan's army from the Peninsula and his letter to that commander under date of Oct. 28, 1863, was the only official explanation of the removal of McClellan from the command of the army of the Potomac, Nov. 7. 1863. When General Grant was made lieutenant general March 12, 1864, by special act of congress creating the rank for him, General [p.42] Halleck was made his chief-of-staff, and continued in Washington until April 19, 1865, when he was transferred to Richmond, Va., as commander of the military division of the James. His orders to the officers in command of the forces operating in North Carolina against the army of Gen. Joseph E. Johnston, "to pay no regard to any truce or orders of General Sherman respecting hostilities" and "to push onward regardless of orders from any one except General Grant and cut off Johnston's retreat," caused a breach in the long existing friendship between the two commanders. On Aug. 80, 1865, he was transferred to the command of the division of the Pacific and on being relieved by Gert. George H. Thomas was transferred to the division of the south, with headquarters at Louisville, Ky. March 16, 1869. He was elected professor of engineering in the Lawrence scientific school, Harvard university, in 1848, but declined the appointment. Union college conferred on him the honorary degree of A.M. in 1843, and that of LL.D. in 1862. He delivered before the Lowell institute, Boston, Mass., in the winter of 1845-46, twelve lectures on the science of war, which were published as" Elements of Military Art and Science" (1846, 2d ed. 1861), and this work became the manual for volunteer officers of the civil war. During his seven months' voyage to California around the horn, he translated Baron Jomini's "Vie Politique et Militaire de Napoleon" which he published in 1864. He also published: A Collection of Mining Laws of Spain and Mexico (1859); a translation of DeFooz on the Law of Mines with Introductory Remarks (1860); and International Law on Rules regulating the Intercourse of States in Peace and War (1861), condensed and adapted to use in schools and colleges (1866). He died at Louisville, Ky., Jan. 9, 1872.

Elizabeth Hamilton, wife of General Henry Wagner Halleck,
was the daughter of Col John Church Hamilton, and granddaughter of Alexander Hamilton.

COL. JOHN CHURCH HAMILTON, lawyer, born in Philadelphia, Aug. 22, 1792, while his father was Secretary of the Treasury, died in Long Branch, N.J., July 25, 1882. He was one of the six sons of Alexander Hamilton, soldier and statesman. His mother was a daughter of Gen. Philip Schuyler. While the death of Alexander Hamilton, in consequence of the historic duel with Aaron Burr, left the family in straitened circumstances, the subject of this memoir was, nevertheless, able to graduate in 1809 from Columbia College. He was admitted to the bar, and engaged [p.296] in the practice of his profession. During the War of 1812, he served as an aid on the staff of General Harrison, with the title of Colonel. Originally a Whig, he joined the Republican party before the Civil War, and admired and supported General Grant, and at one time he ran for Congress. Marriage placed ample means at his command, and Colonel Hamilton then gave himself up to study and literary pursuits. In 1834-40, he published the "Memoirs of Alexander Hamilton," in which he brought the life of his father down to the tragedy which ended it, but, with a delicacy of sentiment characteristic of him, made no mention of that event. His "Works of Alexander Hamilton," in two volumes, appeared in 1851. In 1850-58, he published a "History of the Republic, as traced in the Writings of Alexander Hamilton," in seven volumes. He was married Dec. 20, 1814, to Miss Maria Eliza Van den Heuvel, daughter of Baron John Cornelius Van den Heuvel, once Governor of Dulde, Guiana, and a leading merchant of his day, who lived at the corner of Barclay street and Broadway and owned a handsome estate at Bloomingdale. Mrs. Hamilton died in 1872. Nine children survived their father: Alexander Hamilton, of Tarrytown; Gen. Schuyler Hamilton, of Jamaica, N.Y.; Judge Charles A. Hamilton, of the Supreme Court of Wisconsin; William Gaston Hamilton, civil engineer and vice president of The Mexican Telegraph Co.; Elizabeth, who first married Major General Henry W. Halleck, and after his death Major General George W. Cullum; Mary E. wife of Judge Charles A. Peabody; and Charlotte A., Adelaide and Alice W. Hamilton.

BILLINGS, Frederick, lawyer, was born at Royalton, Vt., Sept. 27, 1823; son of Oel and Sophia (Wetherbe) Billings. When he was quite young his parents removed to Woodstock. He attended the Kimball union academy and was graduated from the University of Vermont in the class of 1844. From 1846 to 1848 he served as secretary of civil and military affairs to Governor Eaten. He was admitted to the bar in 1848, and soon after accompanied a brother-in-law to San Francisco. While they were in New York, waiting for a steamer to the Isthmus of Panama, news came of the discovery of gold in California, and young Billings was the first lawyer to display his sign in the embryo city of San Francisco. On his passage out Mr. Billings met Archibald C. Peachy, a young lawyer from Virginia, and soon after their arrival in San Francisco they formed a partnership as Peachy & Billings. Later Lieut. Henry Wager Halleck was taken into the partnership, and also Trenor W. Park of Vermont, and for many years Halleck, Peachy, Billings & Park were the leading law firm of San Francisco. Mr. Billings at the outbreak of the war did signal service in preventing the secession of the state, and the legislature of [p.295] California, by resolution, requested President Johnson to give him a cabinet position.

Herringshaw's Encyclopedia of American Biography of the Nineteenth Century.
page 439

HALLECK, HENRY WAGER, soldier, author, was born Jan. 16, 1815, in Westernville, N.Y. He was a major-general who was general-in-chief of the armies of the United States in 1862-64. He was the author of Bitumen, Its Varieties, Properties, and Uses; Mining Laws of Spain and Mexico; Elements of International Law; Treatise on International Law; and Elements of Military Art and Science. He died Jan. 9, 1872, in Louisville, Ky.